district



Jan, 9, 1923.

K. P. McELROY.

FIXATI ON 0F NITROGEN.

H'LED MAY 17, 1920.

Patented Jan. 9, 1923 UNITE S'lltTllitl rrica.

Application llltltl May 17, rare. llerial Nu. 382,15tl.

To all '1 07mm it may concern Be it known that I, Kant POMEROY livid :ELROY, a citizen of the United ldtates, residing at Washington, in the District olf (lo-- lumbia, have invented certain new and use :tul Improvements in l iiration o'i lflitrogen, of which the following is a specification.

This invention relates to fixation of nitrogen; and it comprises a method oil" producing ammonia wherein a pervious charge com-- prising an alkali (potash, soda or baryta) and a catalytic metal (iron, cobalt or nickel.) is alternately treated with hot gases containing nitrogen and carbon monoirid and with steam; all as more fully hereinafter set forth and as claimed.

Oi the very many ways of lining nitrogen which have been proposed from time to time but few have gone into actual commercial;

practice. One oi these :tew successful methods was that of Mond wherein. barium carbonate was mixed with. finely powdered coke and formed into briquets which were then exposed to the action of nitrogen or producer gas at a high temperature, iorn ing barium cyanid. The carbon oil? the echo disappeared as carbon IIlOllOXlCl. The barium cyanid was afterwards steamed to produce ammonia and reproduce barium carbonate or other oxidized compound. The sensible heat of the gases was, for the most part, relied upon to give the temperatures necessary; and to secure an economy of heat a pic rality oi chambers were used, the bot gr being sent tl'irough these inetl'iodically in a well understood way. in. the op tion oi? the process however certain prac dilliculties arose which eventually ledto dis continuance among thesebeing the great amount of labor required in making and handling briquets and the rapid contamination of the baryta by colre ash.

It is an object of the present invention to improve on this method by obviating the stated disadvantages while securing cert in new advantages. To this end in lieu of can ploying perishable briquets requiring h and ling and renewing, suitable permanent reaction members or contact meinliiers containing baryta (or another alkali) and. catalytic metal (cobalt, nickel or iron) are used. The carbon necessary i'or reduction and for forming cyanid is produced ir "e contact menu here by the ction oil? the catalytic metal. on

carbon mononid. This carbon is ashless, finely divided and highly reactive while its production is attended by a development of heat 'WlllCl'l much accelerates heating up the ch "go after the steaming or ammonia produping operation.

.lIn the gasiiication of carbon in a producer to 'liO ilrl carbon monoirid although much heat is evolved a still greater quantity disappears or is rendered latent and the car bon mono; produced. has a strong ten dency, throughout a range of temperatures extending up to perhaps 800 or 960 G, to brealr up into carbon dioxid and solid car-- bon with development of heat. This action is catalyzed. by many metals. Iron, cobalt and niclrel all catalyze energetically and, as it happens, these metals also catalyze the formation of cyanide from allralies, carbon and nitrogen. lhe catalytic metal in the reacti a members oi the present invention therefore has several. functions; it produces ashlcss carbon, aids in heating up after steaming and aids in forming cyanid.

llhe reaction members may be assembled from metal and alkali in any. convenient way giving shapes adapted for thorough gas con tact while not opposing undue frictional rcsistance to the passage of gas currents. It is genei y best to incorporate more or less 131] with the allrah, and particularly potash or soda is used, to help in lre'ephe mass open. In one way olt manutac s of r aanded metal or wire net :y be tilled with granular double magnesia or dolomite such as on ior li .ing basic furnaces; this ula material, having lirst been impregled with a salt oi. iron, cobalt or nickel and with a t oi potassium, sodium or barium. it little lithia may advantageously be used in connection with the alkali. These bones may then be stacked in a suitable cltiainber like the bricks in an ordinary clicclzerworlr regenerator. instead of using previous metal blocks, magnesia briclrs may be impregnated with metal and alkali and assembled checlrerworlr. An excellent reaction niemliier is given by bonding granul; commerc ".l magnesia or dolomite retraces into open-textured briclrs with the aid i and a high heat, and there 'mpr n i llut ll find bones of wire netting or ""GI 1 tl1(lGtl metal containing material of the boxes.

an open textured contact mass are best since they resist volume changes in the reaction due to de osition and disappearance of carbon, pro notion of cyanid, etc., better than bricks. Iron or the heat-resisting steels and alloys (such as nichrome) may be used as the In lieu of either bricks or boxes, I may use ordinary strong metallurgical coke, impregnated with catalytic metal and alkali. As carbon deposited by catalysis is much more reactive than coke carbon, coke fragments used as a carrier will last for a long time. After a time, bricks are apt to crumble, and it is an object of the present invention to produce a permanent reaction member.

The reaction chamber can be built in any suitable way and of any suitable material. A steel chamber lined with magnesia or dolomite bricks does very well. It should be provided with'steam and gas inlets and ammonia and gas outlets; and it should also be provided with a filter member in the gas inlet line containing charcoal or coke to keep dust out of the reaction chamber. If potash or soda is usedas the alkali it is desirable also to provide the gas outlet with a charcoal filter to hold back cyanid fumes.

As the source of gas any gas producer may be employed. The hotter the gas is the better, and for this reason, and others, I recommend a slagging gas producer with gas taken off from the hot zone. Blast furnace gas, especially gas from the hot or bosh zones, is also suitable. If ordinary producer gas is employed it is usually desirable to step up its temperature somewhat by the aid of stoves or regenerators since the final or cyaniding reaction takes place quicker at temperatures above 1000 C. than at lower heats. However, temperatures between 800 and l000 also give cyanid.

In the accompanying illustration I have shown, more or less diagrammatically, in central vertical section, certain apparatus within the described invention and susceptible of use in performing the described process.

In this showing, element 1 is a. reaction chamber lined with basic brickwork 2. As shown, the lining is provided near the bottom with inward extensions 3 on which rests a charge of reaction members 41, leaving a clear space 5 below and a clear space 6 above. Through the wall pass a steam pipe 7 and an ammonia exit 8, both being suitably valved. Near the top enters conduit 9, provided with gas filter 10, for hot gases. As shown, gas from a suitable producer or blast furnace (not shown) enters through 11 and may pass directly by 12 to said conduit or it may pass by 13 to a stove or preheater 14. As shown, this stove contains tile or other piping 13 through which gas may pass. At the top, the stove is provided with firing means consisting, as shown, of gas inlet 15 and air inlet 16 and at the bottom it has waste gas outlet 17 leading to a chimney stack or other place of disposition. Leading from the bottom of the reaction chamber is a gas outlet conduit 18 provided with charcoal filter 19.

In the use of the structure shown, presuming the charge to be cold and to consist of barium carbonate and iron (oxid) on a suitable carrier, hot producer gas is ad mitted through 9 and passes downward. As the charge heats up, the iron becomes reduced and catalyzes the decomposition of carbon monoxid, producing a deposit of hot reactive carbon. the temperature of the mass going up rapidly. After a time a evaniding temperature is reached and the deposited carbon and the barium carbonate react together with nitrogen to form barium cyanid and carbon monoxid. In the first or heating up stage when carbon is deposited, the outgoing gas passing away through 18 contains much carbon dioxid, but in the second or cyaniding stage the gas coming oil' through 18 is enriched in carbon monoxid. The two grades of outgoing gas may be separately collected and used for such purposes as may be desired, or they may be mixed and averaged as to composition and calorific value. In the cyaniding stage the quantity of heat consumed is considerable and this is furnished as sensible heat of gas coming in through 9.

After the charge is cyanided, the flow of gas is interrupted. The charge may or may not then be allowed to stand for a time to cool. Steam (or atomized water) is blown in through 7. Water vapor passes through the charge, forming ammonia which passes together with the excess of steam through 8 to suitable collecting means (not shown). When the cyanid is reconverted into carbonate, the steam is cut off and gas once more introduced, and so on indefinitely.

Where the gas used is not hot enough for the present urposes. it may be heated in the stove. 0 this end gas entering at 11 instead of passing directly into the reaction chamber through 12 is sent through 13 and the piping 13 and heated by the combustion of gas from 15 and air from 16. As the temperature of the charge reaches about 800 cyanidation begins and becomes very active at about 1000 C. In cyanidation the 1 barium carbonate is reduce by the reviously deposited carbon, giving barium cyanid and carbon monoxid. The latter joins and enriches the gas.

While for the sake of simplicity of illustration I have shown but one reaction chamher it will be understood from 3 to 6 operating together but out of phase can be employed. In such a mode of operation. the gas introduced into steamed chamber i in circuit to receive the emerging gas and so on till the first steamed charge is hot enough to be cyanided when it is treated with fresh very hot It, for example, hot bosh gas of 12500" or l/lOU C. from a blast furnace (which greet-ally carries cy anid in fumes) available and presuini. the reaction chamber shown to con ain a charge at, say 800, the gas is sent i 11, 11:33, 10 and 9 to the reaction chamber. .11 filter 10 it drops all its eye; id as 'Wfill. flying (E t which it may contain. out at l. somewhat enriched in oxid and somewhat cooled, soy to 900", it will be sent to the inlet 11 of a similar ap-- paratus at a somewhat less advanced stage In this second apparatus it deprived of much 0i its sensible heat, heating; the charge to, say, 800. It does not here dro'g much carbon, the temperature being too high. Passing to the next apparatus however at a lower temperature it here deposits carbon and heats up the charge. This next apparatus maybe one which ha not been steamed.

In using ordinary prom zcer the same routine may be employed, the stove It being only einployodfor the last or cyaniding stage.

After a charge is cyanided however, it

cannot Well be employed for heating up containing; CO for the reason. that at ten'lperatures ranging; below 800 there a tendency for tho reaction to reverse, carbon inonoXid reoonvertinp; the cyanir'i into carbonate.

What I claim is:--

1, In. the fixation of nitrogen, the proc ess which CUlIlplTlSQS alternately exposing.- a contact mass containing; alkali and cat lytic metal to the action oi hot containir ogen and carbon. inononid and to the acrien of us, said at first depositing of the carbon lnonoeicyanld at the expense with reformation of alliali, and repeating the treatments.

3-3, In the fixationv or nitrogen, the method which. comprises providing a suitable tion chamber with a pc ious charge corn ti 'ninp' alkali and cata tic rectal and in succession depesitn carbon in said charge by treatment with carbon. lllOIlOKlCl at a relatively lo v temperature, converting the alkali and carbon into cyanid by nitrogen at a higher teinperatr'e and producing ammonia with reformation of: alkali by steam, said succession. being continued a purality 01': times.

l. In the iizration of nitrogen, the process Which comprises the combination. of the three successive steps of heating a contact containing alkali and a catalytic metal by contacting therewith containin carbon nionoxid, at a temperatiure below 500 C. whereby carbon is deposited in said contact mass iroln said carbon. mOHOXid by .ubherinic reaction, (53) continuing the ing oif said contact mess and deposited GZtI'Ll'JOD, by contacting therewith nitrogencarryingof a temperature above 800 C. whereby cyanid is formed in said contact mass, and (3) cooling and steaming; said contact mass containing cyanid whereby ammonia is formed and alkali rer'cnerated.

In testimony whereof, l: aihi: my signature, 

